Group psychotherapy research lacks a general integrating theory, in particular one which takes into account individual personality features together with group social system characteristics. The present proposal approaches this deficit through the application of principles derived from General Systems Theory. The therapy group is conceptualized as a developing system progressing through stages, each with a specific developmental task. For each stage, role functions are identified which form the critical organizational axes along which development occurs. Specific hypotheses are developed in relation to the following questions: 1. Can group stages be reliably demonstrated to occur in an established sequence? 2. Can critical incidents be identified at the interface between stages? 3. Do role functions correlate with developmental stages? 4. Does the impact of various roles change over time? 5. Can in-group behavior of individual members be predicted by pre-group testing? Ten newly formed therapy groups will be studied over the first 12 sessions. Group climate dimensions and critical transition events will be used to identify stages. Sociometric techniques will be applied to determine roles. Pre-group personality measures will identify potential role candidates. Data collection will consist of a series of brief questionnaires to be completed by group members at the end of each session, as well as ratings made by trained research personnel based on live observation and audio recoding. Objective measurement of developmental stages with clinically acceptable instruments will provide a methodology of importance to clinical researchers. The application of role theory bridges a significant gap in the literature between the individual in the group and the group as a social system. These findings will provide data of use in improving the efficacy and efficiency of group therapy programmes as found in most general hospital psychiatric units and mental health centres. This preliminary study will establish the methodological base for a more extensive investigation.